Not true. You could have an online WebGL game that requires an account and dynamic server provided data to run. The account would cost money.
EDIT: Added last sentence.
EDIT: Added last sentence.
The App Store also provides marketing, which is huge. Where is the public listing of WebGL games that you can quickly browse and start playing?
I'm not convinced the App Store is a meaningful marketing channel anyway, except for the 0.001% of game developers that can afford to buy downloads and then happen to get lucky in the App Store curation roulette.